Whether one travels to a particular building on a particular day of the week is irrelevant. It's the relationship with God that matters.
But your relationship with God isn't just "vertical," it's also "horizontal," extending through other baptized Christians who, as Scripture tells us, are "the body of Christ." Christ also tells us that "where two or more are gathered in my name, there I am also."
In Christian worship, God is present in Scripture and in the community. In Catholic worship, God is present substantially in the Eucharist, in Scripture, and in the community.